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A Waffle Structured Composite for Rcs Reduction Via Absorption and Scattering Mechanisms

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SSRN 2022年

作者： Jiang, Qian Duan, Jinming Uddin, Azim Wu, Xianyan Yi, Honglei Wu, Liwei Tianjin and Ministry of Education Key Laboratory for Advanced Textile Composite Materials Tiangong University Tianjin300387 China School of Textile Science and Engineering Tiangong University Tianjin300387 China School of Materials Science and Engineering Zhejiang University Hangzhou310027 China Key Laboratory of Yarn Materials Forming and Composite Processing Technology of Zhejiang Province College of Material and Textile Engineering Jiaxing University Jiaxing314001 China

A radar absorbing material named waffle structured composite (WSC) was proposed based on the periodic structure element formed in double-sided knitting process. The unique pattern shaped by the knitted loops achieved the collaborative mechanisms of absorption and scattering. The radar cross section (RCS) below -10dB was achieved ranging from 12 to 18 GHz for WSC in course direction, and RCS reduction peak can reach to -30dB. Through the S-parameter analysis and simulation, the RCS reduction mechanism was revealed for WSC in both wale and course direction. It was found that the low-frequency RCS reduction in the wale direction was mainly dominated by the absorption mechanism, and the high-frequency RCS reduction in the course direction was led by the scattering mechanism. Furthermore, to further explore the scattering and absorption mechanism, phase difference, dielectric loss and magnetic loss were investigated in details. It was verified that the absorption of WSC is mainly originated from dielectric loss with slight magnetic loss, and Debye relaxation plays the important role in dielectric loss. The WSC proposed in this paper is equipped with characteristics of good RCS reduction and continuous large-scale manufacture, which is promising in practical engineering application of radar stealth. © 2022, The Authors. All rights reserved.

关键词： Radar cross section

Up-Shifting the Desalination Rate Limit of Capacitive Deionization Via Integrating Chloride-Capturing Bi Nanocluster with Flow-Through Cell Architecture

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SSRN 2022年

作者： Wang, Lihao Liu, Zizhen Wang, Ziping Ma, Qianhui Guo, Zixin Shen, Genzhe Wang, Kai Xu, Xingtao Liu, Yong Yuan, Xun School of Materials Science and Engineering Qingdao University of Science and Technology Shandong Qingdao266042 China Facility Horticulture Laboratory of Universities in Shandong Weifang Key Lab of Advanced Light Materials Manufacturing and Forming Weifang University of Science and Technology Shandong Weifang262700 China Inner Mongolia Key Laboratory of Environmental Chemistry College of Chemistry and Environmental Science Inner Mongolia Normal University Hohhot010022 China 1-1 Namiki Ibaraki Tsukuba305-0044 Japan

Faradic electrode-directed capacitive deionization (faradic-based CDI) as a green and eco-friendly technique is particularly promising in addressing the freshwater crisis, but its practical applications are plagued by the sluggish desalination kinetic. After deciphering its dynamic desalination process, two rate-determine steps (RDS) are identified, i.e., the ion diffusion inside the faradic electrode (RDS #1) and mass transfer process in the electrolyte (RDS #2). Therefore, we propose a synergetic strategy to upshift the desalination rate limit of faradic-based CDI through the integration of delicate material design with rational cell architecture. Specifically, deploying ultrasmall Bi nanoclusters (impregnated carbon nanofibers;Bi NCs@CNF) as chloride-capturing electrodes and constructing a flow-through CDI (FT-CDI) system to accelerate the diffusion process (RDS #1) and shorten the mass transfer pathway (RDS #2), respectively. As expected, Bi NCs@CNF-based FT-CDI performs super-fast desalinization (0.56 mg g-1 s-1) and excellent cyclic stability. Taken together, our study opens an avenue in upshifting the desalination kinetics of faradic-based CDI based on the joint power of both "material design" and "cell architecture", which may motivate the development of highly-efficient desalination systems. © 2022, The Authors. All rights reserved.

关键词： Carbon nanofibers

Dynamics of Passive-input Overconstrained Deployable Antenna Mechanisms Composed of 3RR-3RRR Tetrahedron Units

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Jixie Gongcheng Xuebao/Journal of Mechanical Engineering 2020年第5期56卷 181-191页

作者： Liu, Wenlan Xu, Yundou Guo, Jinwei Yao, Jiantao Zhao, Yongsheng Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Qinhuangdao066004 China Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of National Education Yanshan University Qinhuangdao066004 China

The dynamic model of a passive-input overconstrained deployable antenna mechanism composed of 3RR-3RRR tetrahedron units is established, and the effects of the number, stiffness and initial compression angle of driving elements (i.e., torsion springs) on the motion of mechanism are analyzed. Based on the structural characteristics and spatial coordinate transformation formulas the relationships between the positions of the centroid of each component and the independent deployment angle of the mechanism are deduced, and then the analytical expressions of velocities of all components are obtained. The movements of all components are divided into translation motion, fixed-axis rotation, plane motion and compound motion according to the characteristic of the degree of freedom (DOF) of the mechanism. For the sake of dynamic analysis of the passive-input overconstrained mechanism, the composite motion of components is further decomposed into plane motion and translation motion along the normal direction of the plane. The dynamic models of the passive-input overconstrained deployable mechanism 3RR-3RRR and its combined mechanism 3(3RR-3RRR)-3RRR-3RRR are built by using Lagrange method. The relationships between the stiffness of torsion springs and the independent deployable angle of the mechanisms are obtained, and the influence of the stiffness and number of torsion springs on the deployable motion of the mechanisms is analyzed. The simulation model of 3(3RR-3RRR)-3RRR-3RRR mechanism is established by Adams software. The simulation is carried out by adding torsion springs with different numbers and stiffness. In addition, the effect of initial compression angle of torsion springs on the deployable motion of the mechanism is discussed. The simulation results verify the correctness of theoretical analyses. The results can provide theoretical guidance for the coordinated control of passive-input overconstrained deployable antenna mechanisms composed of 3RR-3RRR tetrahedron u

关键词： Stiffness

Design and analysis of a truss deployable antenna mechanism based on a 3UU-3URU unit

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Chinese Journal of Aeronautics 2019年第12期32卷 2743-2754页

作者： Yundou XU Jinwei GUO Luyao GUO Wenlan LIU Jiantao YAO Yongsheng ZHAO Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao 066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of National Education Yanshan UniversityQinhuangdao 066004China College of Energy and Power Engineering Lanzhou University of TechnologyLanzhou 730050China

Space deployable structures with large calibers, high accuracy, and large folding ratios are indispensable equipment in the aerospace field. Given that the single-DOF 3 RR-3 RRR deployable unit cannot be fully folded, this study proposes a 3 UU-3 URU deployable unit with two kinds of DOF: folding movement and orientation adjustment. First, based on the G-K formula, the DOF of the 3 UU-3 URU unit is analyzed. Then, the 3 UU-3 URU unit is used to construct a deployable truss antenna with a curved surface, and the DOF of the whole deployable antenna containing multiple 3 UU-3 URU units is calculated. The structural design of a deployable antenna with two loops is carried out with specific parameters and geometric relations. Next, a DOF simulation of a basic combination unit composed of three 3 UU-3 URU units is performed. Finally, a prototype of the basic combination unit is manufactured, and the DOF of the mechanism is experimentally verified.

关键词： Basic combination unit Degree of freedom(DOF) Deployable truss antenna Simulation analysis Structural design

WITHDRAWN: Characterization of the hot deformation behaviour of powder metallurgy Ti–22Al–25Nb alloy by using 3D processing maps

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Intermetallics 2020年

作者： Jia, Jianbo Yang, Zhigang Peng, Weijin Dong, Tiantian Xu, Yan Liu, Hailiang Luo, Junting Education Ministry Key Laboratory of Advanced Forging & Stamping Technology and Science Yanshan University Qinhuangdao066004 China State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao066004 China

Powder metallurgy (PM) Ti–22Al–25Nb (at.%) alloy was prepared by spark plasma sintering under the conditions of 950 °C/80 MPa/10 min. Isothermal unidirectional compression experiments of the PM Ti–22Al–25Nb alloy were completed on the Gleeble-3500 thermal–mechanical simulator at temperature and strain rate ranges of 920 °C–1100 °C and 0.001–10s−1, respectively, and a total height reduction of 50%. The flow characteristics were described by the establishment of constitutive models belonging to the (α2+β/B2+O) three-phase (920 °C–980 °C) and (α2+B2) two-phase (1010 °C–1070 °C) regions. The three-dimensional (3D) hot processing maps regarding temperatures, strain rates and strains were obtained. The optimum processing parameters (temperature and strain rate) were determined. The microstructures of the deformed specimens under various conditions were analyzed to characterize the corresponding deformation mechanisms. Moreover, electron backscattered diffraction (EBSD) measurements were employed to study the mechanisms of DRX. It was determined that the deformation activation energies of the PM alloy corresponding to the (α2+β/B2+O) phase and (α2+B2) phase regions were 763.969 and 685.587 kJ mol−1, respectively. In addition, the results proved that the proposed 3D hot processing maps could reveal the deformation mechanism and microstructural evolution of the PM Ti–22Al–25Nb alloy during hot processing. The main softening mechanisms in the stability regions were dynamic recrystallization (DRX) and lamellar dynamic globularization. The deformation mechanisms of the unstable domains identified from the 3D instability maps were adiabatic shear bands and flow localization. © 2020 Elsevier Ltd

关键词： Spark plasma sintering

A facile,versatile hydrogel bioink for 3D bioprinting benefits long-term subaqueous fidelity,cell viability and proliferation

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Regenerative Biomaterials 2021年第3期8卷 141-155页

作者： Hongqing Chen Fei Fei Xinda Li Zhenguo Nie Dezhi Zhou Libiao Liu Jing Zhang Haitao Zhang Zhou Fei Tao Xu Department of Neurosurgery Xijing HospitalFourth Military Medical UniversityXi’an 710032China Department of Neurosurgery Central Theater General HospitalWuhan 430010China Department of Ophthalmology Xijing HospitalFourth Military Medical UniversityXi’an 710032China Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationDepartment of Mechanical EngineeringTsinghua UniversityBeijing 100084China Department of Neurosurgery Sichuan Provincial People’s HospitalUniversity of Electronic Science and Technology of ChinaChengdu 610072China Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital Chengdu 610072China Department of Orthopedics Fourth medical center of PLA general hospitalBeijing 100048China East China Institute of Digital Medical Engineering Shangrao 334000China Department of Precision Medicine and Healthcare Tsinghua-Berkeley Shenzhen InstituteShenzhen 518055China

Both of the long-term fidelity and cell viability of three-dimensional(3D)-bioprinted constructs are essential to precise soft tissue ***,the shrinking/swelling behavior of hydrogels brings about inadequate long-term fidelity of constructs,and bioinks containing excessive polymer are detrimental to cell ***,we obtained a facile hydrogel by introducing 1%aldehyde hyaluronic acid(AHA)and 0.375%N-carboxymethyl chitosan(CMC),two polysaccharides with strong water absorption and water retention capacity,into classic gelatin(GEL,5%)–alginate(ALG,1%)*** GEL–ALG/CMC/AHA bioink possesses weak temperature dependence due to the Schiff base linkage of CMC/AHA and electrostatic interaction of CMC/*** fabricated integrated constructs through traditional printing at room temperature and in vivo simulation printing at *** printed cell-laden constructs can maintain subaqueous fidelity for 30 days after being reinforced by 3%calcium chloride for only 20 *** cytometry results showed that the cell viability was 91.3861.55%on day 29,and the cells in the proliferation plateau at this time still maintained their dynamic renewal with a DNA replication rate of 6.0661.24%.This work provides a convenient and practical bioink option for 3D bioprinting in precise soft tissue repair.

关键词： bioink bioprinting subaqueous fidelity cell viability

The Microstructure and Quasi-Static Compression Properties at Elevated Temperatures of the Aged Vacuum Die-Casting Mg-4al-4(La, CE) Alloy

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SSRN 2022年

作者： Liu, Xiaoyu Le, Taihe Yuan, Shuai Wang, Jinhui Cheng, Weili Li, Xiaoqiang Jin, Peipeng Qinghai Provincial Key Laboratory of New Light Alloys Qinghai Provincial Engineering Research Center of High Performance Light Metal Alloys and Forming Qinghai University Xining810016 China College of Materials Science and Engineering Shenyang University of Technology Shenyang110870 China School of Materials Science and Engineering Taiyuan University of Technology Key Laboratory of Interface Science and Engineering in Advanced Materials Ministry of Education Taiyuan University of Technology Taiyuan030024 China School of Material Science and Engineering Lanzhou University of Technology Lanzhou730050 China

In this study, the hot compression test of the aged vacuum die-casting Mg-4Al-4(La, Ce) alloy was performed on Gleeble-3500 simulator. The mechanical properties of Mg-4Al-4(La, Ce) alloy were studied at different compression temperatures (100°C, 150°C, 200°C, and 250°C). During the compression, the microstructure evolution, texture, and dislocation slip of the Mg-4Al-4(La, Ce) alloy were systematically investigated by the electron backscatter diffraction (EBSD) technology. The results demonstrated that the flow stress decreased and the plasticity boosted with the increase in temperature. Mg-4Al-4(La, Ce) alloy exhibits excellent strength and toughness with elevated temperature. At 200 °C, it still has compressive strength of 204.5 MPa and compressive elongation of 59%. By observation of the microstructure, it has typical //CD texture after compression. It was found by in-grain misorientation axis (IGMA) analysis that the pyramidal slip is sufficiently activated, which effectively improves the toughness of the alloy. In addition, the dislocations and dislocations are observed at 200 °C. Therefore, the excellent mechanical properties of Mg-4Al-4(La, Ce) alloy at high temperature are the result of grain refinement strengthening, second-phase reinforcement and work hardening. © 2022, The Authors. All rights reserved.

关键词： Strain hardening

Microstructure Evolution and Crack Formation Mechanism of High-Nitrogen Bearing Steel Subjected to Warm Deformation

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SSRN 2022年

作者： Sun, Mengli Wang, Feng Qian, Dongsheng Liu, Xiaoyu Wu, Min School of Materials Science and Engineering Wuhan University of Technology Wuhan430070 China Hubei key Laboratory of Advanced Technology for Automotive Components Wuhan430070 China Hubei Engineering Research Centre for Green Precision Material Forming Wuhan430070 China Aero Engine Corporation of China Harbin Bearing Co. Ltd. Harbin150500 China

The high-nitrogen bearing steel, with the addition of nitrogen to replace partial carbon, exhibits excellent hardness and durability properties. However, the microstructure evolution and the relevant crack formation mechanism during warm deformation remain unclear. In this work, the microstructure evolution and deformation behaviors of the X30CrMoN15-1 high-nitrogen steel under warm deformation (700 ℃ and 800 ℃) have been investigated. It is found that the cracks are easily to generate under the low strain rates. The microstructure observation indicates that the warm deformation (both at 700 °C and 800 ℃) facilitates the ferrite transition and the precipitation of carbonitrides. In the specimen deformed at 700 °C, the spherical carbonitrides are precipitated from the grain boundary of recrystallized ferrite, where considerable dislocations are generated. The volume expansion generated by the ferrite transformation is inhibited by the neighbouring lamellar carbonitrides, which leads to the significant stress concentration and even crack initiation. For the specimen deformed at 800 ℃, the accelerated transformation of ferrite leads to the carbon-enrichment of neighbouring austenite, promoting precipitation of carbonitrides from the interface between ferrite and neighbouring austenite. The interfacial debonding and hardness mismatch together contribute to the formation of cracks at the interface between ferrite and M/A island. © 2022, The Authors. All rights reserved.

关键词： Ferrite

MBSE-Based Integration of Superplastic forming Manufacturing Process Information for Customized Products

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Processes 2025年第5期13卷 1497-1497页

作者： Xingwei Zhou Wanran Yang Haiyu Guo Shaozong Wang Boya Wang Le Wu Chengyue Xiong Ailing Zou Bo Wang Fanrong Zeng Gongxi Zhou Shijiang Li Liang Hou Pen-Tung Sah Institute of Micro-Nano Science and Technology Xiamen University Xiamen 361102 China State Key Laboratory of Advanced Forming Technology & Equipment Beijing National Innovation Institute of Lightweight Ltd. Beijing 101407 China

Optimizing superplastic forming (SPF) process parameters is vital for improving production efficiency and addressing the growing complexity of product requirements in high-end manufacturing fields. Current optimization of SPF process parameters focuses on meeting product requirements, often overlooking constraints related to quality indicators, process, and equipment limitations. This paper proposes an optimization approach that integrates SPF manufacturing process information using model-based systems engineering and simulation validation techniques to establish a continuous mapping between product requirements, process parameters, and equipment control parameters. First, SPF is modeled using the systems modeling language to describe the relationships between processes and equipment. Then, the process parameters are extracted via object flow analysis and categorized according to shape and performance control. The key process parameters and impact indicators for meeting customized product requirements are identified using the analytic hierarchy process. Finally, orthogonal experimental design and process simulation are employed to optimize the parameters, with the results mapped onto the physical model to guide the equipment control parameter design. A case study demonstrates its feasibility and effectiveness in meeting customized products.

关键词： model-based systems engineering superplastic forming customized products process parameters